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IO Moth Lifecycle

Correction: I misidentified two Photos of the Day, a few days ago. They labelled the “first sightings” in Judi’s Gardens as “Zebra Swallowtails” when in fact they were Tiger Swallowtails. I knew that. I was just being stupid. I apologize. The labels have now been corrected, if you look in the Photo of the Day archive. – Greg

Updates to the following post made on 9/27/2010.

The very first thing any post about Io Moths needs to make clear is do not touch the caterpillars! Do not touch the caterpillars! Do not touch the caterpillars! Are three warnings enough? I hope so, because if these caterpillars come into contact with your skin, however lightly, you’ll have a terrible, ichy rash to show for it. It’s okay to wear those disposable latex gloves (even the ones that contain no latex :). Just be careful!

Click on any picture to see a larger version.

That out of the way, this is what the eggs look like:

They’re laid in rows, all in a square or rectangle, or at least a rough polygon. They’re white, each with a blue spot on top and a yellow spot on the side. They’re quite striking:

As the caterpillats hatch out, in their first instar, they breakfast on the eggshells (you can see a couple in the act of hatching in this picture):

Here are first (or at least early) instar caterpillars. They stay in a group and travel and eat together:

Soon they begin to show hints of the stripes that will later be so colorful down their sides:

As they get bigger, the groups divide into several with fewer caterpillars in each. And as the instars progress, they go from brown to yellowish. Here are different instars together:

Here, again, are four presenting a couple of instars. The one on the right has achieved the green color with the red and white “racing stripes” that characterizes the final instar:

This caterpillar has just fnished molting. In this picture and the previous one, you can clearly see the tiny spines, which are like miniscule hypodermics waiting to inject you with rash-inducing poison if you aren’t careful::

The next three photos are of the final instar caterpillar: A lovely lime green with bright stripes. Beautiful and dangerous!

Here are a couple of cocoons. The actual cocoon is “inside there,” surrounded by a mesh-like membrane that’s sticky, and knits together a coating of leaves or other debris that surrounded the area where the caterpillar pupated. In the first picture, I’m not sure the pupating has completed, because you can still see the caterpillar’s colors. In the second, you can see that the cocoon is a dark brown:

You don’t need to hang the cocoon. If you leave it on the bottom of a mesh cube, the moth can climb and set its wings when it emerges. And they are striking wings. Here they are spread out:

When the wings are closed, it hides the colorful eye spots:

Another picture with the wings spread:

Update, 9/27/2010: Coloration varies according to gender. The moth above, light and brownish, is male. This one, dark and much more red, is female:

Update, 9/27/2010: One notable thing about Io’s in their moth form is that they do not drink nectar. The Io lives (for about a week) entirely off body fat that was stored up during the caterpillar phase. The Io lives only to mate and lay eggs.

If you want to raise IO Moths, get yourself a box of latex gloves (get the ones that don’t contain latex is you’re allergic). And be sure you raise the caterpillars in some kind of contained, protected area where they won’t accidentally come into contact with you or anyone else. It’s up to you to be a responsible IO Moth parent!